Electromagnetic display device



May 22, 1962 J. R. KNIGHT ELECTROMAGNETIC DISPLAY DEVICE Filed Dec. 30, 1958 ATTORNEY 3,036,300 ELECTROMAGNETIC DISPLAY DEVICE John R. Knight, Hyde Park, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Filed Dec. 30, 1958, Ser. No. 783,804 1 Claim. (Cl. 340373) This invention relates to display devices, and more particularly to an element of an automatic matrix display board. These boards may be of the type used, for example, to convey information at sporting events, stock exchanges, etc.

There are, in general, two classes of automatic display boards: (1) those which utilize lamps selectively illuminated in patterns, and (2) those which comprise matrixes of selectively movable elements which present contrasting appearances when in different positions and which are made visible by ambient light. My invention pertains to the second class and is characterized by low power requirements, low maintenance and initial costs, high reliability, and good visibility under high ambient light conditions.

In accordance with the principle of my invention the selectively movable matrix elements embody individual permanent bar magnets coacting with respective stationary solenoids, the latter being energizable in either direction to reverse the position of the related element. Once the element is reversed the related solenoid is de-energized and the element is self-detented in its new position by the field induced in the soft iron core of the solenoid by the permanent magnet. Therefore, no power is required to maintain a setting of the display board.

In a preferred form of the invention the matrix elements are rotatable ball-shaped bodies, such as spheres or spheroids and are contrastingly colored on the opposite halves respectively presented when the elements are reversed. This configuration gives the board a wide angle of discernability.

Accordingly, it is an object of my invention to provide an improved automatic display board which requires power only to change the display and not to maintain the display.

It is a further object of the invention to provide a display board of the type comprising matrixes of selectively movable elements which are self-detenting.

Another object is to provide an improved display board having a wide angle of discernability.

Other objects of the invention will be pointed out in the following description and claim and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode which has been contemplated of applying that principle.

In the drawings:

FIG. 1 is a cross-sectional view of a single display matrix element embodying my invention.

FIG. 2 is a front elevation of a matrix embodying matrix elements in accordance with my invention.

In the illustrative form of the invention shown in the drawing FIG. 2 exhibits a matrix for showing, in a conventional manner, by selective reversal of appropriate ele ments of the matrix, a single character of a display. A single one of the elements making up the matrix is shown in detail in FIG. 1.

In this illustrative embodiment of the invention each element comprises a ball-shaped body 10, preferably in the form of a sphere or spheroid, having a permanent magnet 13 rigidly afiixed inside of it. The ball-shaped body 10 has one-half of its surface 11 of a dark color, and the other half 12 of a light color, each of these surfaces being associated with a pole of the permanent magnet 13. The ball-shaped body 10 is pivoted about a horiatent O 3,036,300 Patented May 22,1sa2

zontal axis 14 which passes through the body 10, at the junction of the light and dark halves, and has its axis parallel to the surface of the display board 20. A sole' noid 15 with a soft iron core 16 is rigidly positioned in close proximity to the rear surface of the body 10. The axis of the solenoid is perpendicular to horizontal axis 14 When no voltage is applied to the line 17, the pole ofthc permanent magnet 13 nearest to the solenoid will induce a magnetic field in the soft iron core 16. This induced field will cause the end of the core 16 adjacent to the body 10 to assume a polarity opposite to that of the inducing pole of the magnet 13. These poles will attract causing the body 10 to rotate until the axis of the magnet 13 is in line with the axis of the core 16, in which position Thus, once a pole of the magnet 13 has been fixed in association with a colored surface 11 or 12, of the body 10, the desired color can be brought to the viewing surface by applying a voltage of predetermined polarity to the terminals 21 and 22. When a number of these electromechanical units are assembled in matrix form, as shown in FIG. 2, the outline of any alphabetic, numeric or special character can be formed by the selective application of voltages to the terminals 21 and 2.2 of each unit.

Since the body 10 is detented in a desired position by the magnetic attraction of the magnet 13 to the soft iron core 16, power is required only to rotate the ball-shaped bodies. This power may be supplied and controlled as shown in FIG. 1 by a battery 19 controlled by a reversible switch 18 or in any of several other conventional manners. It may be preferable to displace the axes of the individual elements to preclude adverse interaction of adjacent elements.

With a face plate 20 of the same color as one of the body surfaces 11 or 12, the color contrast of, for example, a white body on a dull black surface, will be sufficient to give excellent discernability under upper medium to high ambient light conditions. The lower range of discernability may be extended by including a source of frontal lighting with the display board.

Another feature of my invention is its wide angle of discernability. Using spheres, or spheroids, with one-half of each visible to the viewer, the characters displayed will be visible over a relatively wide angle.

High reliability is obtained in my device by utilizing a minimum of moving parts and by the use of long life elements. This reliability, coupled with the inherent simplicity of the device results in low maintenance expenses.

My device can be fabricated in any desired size and by use of lightweight materials, such as plastics, its overall weight can be kept relatively low. Liberal tolerances, simplicity of fabrication, and the use of inexpensive materials will yield the added advantage of low initial cost and this, coupled with low maintenance, will make this an economical system.

While there have been shown and described and pointed out the fundamental novel features of the invention as applied -to the preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claim.

What is claimed is:

A display device consisting'of:

a body;

means for mounting said body for rotary movement about the bodys'axis; v

a bar magnet having poles of opposite polarity rigidly fixed in said body in a position perpendicular to said axis;

V a soft iron core having an end rigidly fixed adjacent said body, said end being adapted to have induced therein; by the adjacent pole of the magnet, a pole of opposite polarity to the inducing pole, the mutual attraction of the inducing pole and the induced pole causing saidbody to be rotated to a first stable position in which the gap between said induced pole and said inducing pole are a minimum and positively detentin'g the body in that position; and,

means for momentarily reversing the polarity of said end, causing a mutual repulsion between saidrend and said adjacent pole resulting in a rotation of said magnet to a point where its opposite pole is separated References Cited in the file of this patent UNITED STATES PATENTS 2,415,452 Taylor et a1 Feb. 11, 1947 2,585,974 Taylor et a1 Feb 19, 1952 2,740,955 Barrett Apr. 3; 1956 2,836,773 Skrobisch May 27, 1958 OTHER REFERENCES Siemens-Schucke'rtwe'rke': German application Ser. No; 535542, printed July 5, 1956 (K1 21045). 

